P0572

DTC P0572

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



DTC Descriptor
DTC P0572 00
- Brake Switch Circuit 1 Low Voltage




Diagnostic Fault Information






Circuit/System Description

The brake applied signal circuit is a direct hardwire input from the body control module (BCM) to the engine control module (ECM) and transmission control module (TCM). The ECM monitors the brake applied signal circuit to detect when the brake pedal has been applied. The BCM monitors the brake pedal position (BPP) sensor to determine when the brake pedal is applied. When the brake pedal is applied, the BCM sends a GMLAN serial data message to the ECM indicating that the brake pedal has been applied. The BCM sends a voltage signal on the brake applied signal circuit to the ECM and TCM.


Conditions for Running the DTC

* The ignition is ON.
* The engine is running.
* Battery voltage is greater than 11.5 volts.



Conditions for Setting the DTC

The ECM detects a low voltage signal when the serial data message from the BCM indicates the brakes are applied.


Action Taken When the DTC Sets

* The ECM stores the DTC to memory.
* The ECM will record the operating conditions at the time the diagnostic failed. The ECM stores this information in Failure Records.



Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 40 malfunction-free ignition cycles have occurred.



Reference Information
Schematic Reference

* Cruise Control Schematics (Electrical Diagrams)
* Automatic Transmission Controls Schematics (Electrical Diagrams)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Cruise Control Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information


Circuit/System Testing

1. Ignition OFF, disconnect the harness connector X1 at the ECM.
2. While applying the brake pedal, test for 11.5-12.2 volts between the signal circuit terminal 7 (LAT/LY7) or terminal 9 (LZ4) and ground.

• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

3. If all circuits test normal, replace the ECM.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.


Control Module References (Programming and Relearning)for ECM or BCM replacement, setup, and programming